When processing natural fibers, especially cotton, the quality assurance is one of the most important points. By constant monitoring of the fed raw product by means of samples taken at random it must he guaranteed that the demanded quality can be kept and that no problems occur during the processing.
The quality and the market value of the fibers are determined by means of quality factors such as length, length uniformity, strength, elongation, trash, color, micronaire and fineness. In order to automatize the standardized tests developed for this purpose different efforts have been made. The preparation of the test material was however normally carried out by hand or in at least partly automatized manner.
The preparation of the fibers to be tested contains different stages. First a certain amount of fibers must be extracted from the supplied raw fibers. Then the fibers are mostly first subjected to an optical test in which the proportion of foreign matter and the color are determined.
In order to test the distribution of lengths of fibers and the tensile characteristics such as strength, elongation and related properties, the fibers must be gripped mechanically and ordered or arranged respectively. In this context the words "carding" and "combing" are used. Carding is the opening of the fiber balls and rough arrangement of the fibers. Combing is the bringing of the fibers into the definitive parallel position. The most common method for extracting fibers, which can be found partly as different variants to be operated purely manually and partly as automatized variants, always bases on a drum with a perforated surface, whereby the perforations are on the outside of the circumference of the drum. The balls of fibers are filled into these drums and then pressed against the perforated surface from the inside by means of a mechanical device such that part of the balls of fibers protrudes through the holes on the outside. By means of a device arranged concentrically to the periphery of the drum and movably along the surface a certain amount of fibers can then be extracted from the balls and gripped by a clamp. These preparations are usually carried out manually.
An attempt at automation was made in U.S. Pat. No. 5,178,007. With this arrangement it is however obvious that the originally manually operated apparatuses were substantially copied, combined on a platform and automatized. The mechanical processes in the preparation of the fibers, which in the manual preparation mainly base on rotation movements, are unfit for automation. No effort was made to optimize the processes and make them meet the requirements of automation. A testing machine was to be constructed to be as simple and as precise as possible in order for there to be no loss in the reproducibility of the test results. The automatized solutions such as e.g. the apparatus described in U.S. Pat. No. 5,178,007 do not comprise these very characteristics. They are usually very complex in construction due to that e.g. rotation movements were chosen instead of straight movements.
In the automation of movement processes connected in a row it is often unfavorable if the originally manually operated processes are taken over without adaptation and solely the human operator is subjected to automation. This kind of solution is generally very complex mechanically is processes favorable to a human being are not necessarily optimal for a machine. In connection with this kind of solution the term "mechanized hand" is used.